1. Field Of Invention
This invention relates to manually operated corkscrews of the first-class lever type.
2. Description Of Prior Art
All previous corkscrews of the first-class and second-class lever types require two-handed operation, i.e. one hand to hold and stabilize the bottle and/or the fulcrum against the bottle, the other hand to apply an opening force.
Most pocket corkscrews are of the second-class lever type. A second-class lever places the load between a fulcrum, at one end of the lever, and a free end of the lever with which to apply a force. The load moves in the same direction as the applied force. In a corkscrew, this mode of operation lifts the cork out of the bottle in the same direction as the movement of the free end of the lever. The applied force moves the corkscrew lever away from the bottle. Hence this is an unstable procedure that requires use of two hands, one hand to stabilize the bottle and the fulcrum against the bottle lip and one hand to apply the force against the free end of the corkscrew. It also requires the use of both arms and shoulders, and some strength. This operation can be difficult for small people or those with physical limitations.
A seesaw is a first-class lever; a force at one end of the lever moves a load on the opposite end of the lever in the opposite direction to the applied force. Corkscrews of this type have been in use since the 1800s, but have not been popular for reasons that will be made apparent. The fulcrum is located between the screw and the applied force. The screw, at one end of the lever, is driven into the cork. Then the fulcrum is placed against the bottle lip. A force is applied downward on the free end of the lever. This results in the screw being lifted up, pulling the cork with it. The basic advantage to a first-class lever corkscrew is that the bottle can be placed on a stabilizing surface and the body weight becomes the applied force. Without placement on a stabilizing surface this operation can be more difficult than with a second-class lever corkscrew. This is because the body weight has nothing to push against except the strength of the operator, who must hold the bottle stable while applying a force that moves past the bottle rather than towards the bottle. Other disadvantages will be described later.
All previous pocket corkscrews have been designed for use with two hands; one to apply the force while the other hand holds the bottle stable and simultaneously holds the fulcrum in place. Only one prior art addresses the need or benefit of one-handed operation. Though U.S. Pat. No. 262,613 to Pitt requires only one-handed operation for removal of the cork, his device, using a direct pull, does not create any mechanical advantage. It also requires the bottle to be positioned on a table top or held in a second stabilizing hand. However, one-handed operation could be accomplished with a first-class lever corkscrew. The lever being shaped in a manner such that when a thumb is grasped around the bottle neck the free end of the lever is within the grasping range of the fingers of the same hand. Then, squeezing the grip will pull the free end of the lever towards the bottle and the screw end of the lever will be forced away from the bottle, extracting the cork. A very stable situation is created since only one body part, i.e. the hand, is used to move both the bottle and the free end of the lever towards each other, i.e. towards a common center-of-gravity. The fulcrum can be angled towards the screw at the bottle lip when the corkscrew is engaged for use, and is thus stabilized solely by being pushed towards its engagement with the bottle lip. Mechanical advantage can be added by utilizing fulcrums of different functional lengths. This will allow the cork to be raised less distance with each squeeze. Only one hand then is necessary to apply the force and hold both the bottle and the corkscrew stable during use.
First-class lever corkscrews with only one fulcrum require a large arc through which the lever must move to completely extract the cork. U.S. Pat. No. 280,697 to White, U.S. Pat. No. 984,661 to Halk and FR 2,770,209 to LeFebvre solve this problem by having multiple attachment points along the shank of the fulcrum to effectively create a set of multiple length fulcrums. U.S. Pat. No. 1,213,034 to Sowers uses multiple attachment points along the shank of the screw. U.S. Pat. No. 6,032,553 to Puig uses a complex ratchet design. In all of these the free end of the lever is to be held in a perpendicular, or an elevated position, relative to the bottle, allowing the person to use their body weight to press on the free end of the lever while stabilizing the bottle on a table top with the other hand and thus ruling out one-handed operation. The fulcrums are meant to be held against the bottle lip by the hand not applying the force.
First-class lever corkscrews are sensitive in two ways to the distance between the fulcrum's pivotal mount on the lever relative to the screw's pivotal mount on the lever.    1. The closer together the pivotal mounts of the fulcrum and screw are on the lever the more the free end of the lever points in a more elevated position when the corkscrew is engaged for use. As the pivotal mounts of the fulcrum and screw get further away the free end of the lever points lower when the corkscrew is engaged for use. The difference in lever position is large in just a few millimeters of relative pivotal mount displacement. The lever's angle relative to the bottle neck affects the convenience of use and the distance the cork is lifted with each movement of the lever.    2. As the fulcrum's pivotal mount point moves away from the screw's pivotal mount the fulcrum becomes more perpendicular to the screw. If the pivotal mounts become far enough away there will not be a lifting action of the screw but rather the screw will be pulled sideways, compressing the cork against the neck of the bottle. If the pivotal mounts get too close together the fulcrum will be driven off the bottle lip or the cork hardly moves at all.Other problems with first-class lever corkscrews are:    1. Straight-out removal of the cork is difficult to achieve consistently as it is easy to misdirect the applied force and to translate the screw perpendicular to the desired direction, thereby compressing the cork against the bottle neck.    2. Getting the fulcrum to stay in place on the bottle lip during operation.    3. Creating mechanical advantage for ease of use.
The solution to the above problems has been to create a series of levering operations. This creates mechanical advantage, decreases sensitivity to the distance between the screw's and fulcrum's pivotal mounts and helps to keep the forces balanced so that the cork is lifted straight out from the bottle neck. FR 2,770,209 to LeFebvre accomplishes this with a fulcrum that has multiple attachment points along its shank. U.S. Pat. No. 1,213,034 to Sowers allows for changing the screw's length by allowing the attachment point along the shank of the screw to change. This creates a similar solution to LeFebvre. U.S. Pat. No. 6,032,553 to Puig uses a ratchet system which is complicated to use. The above solutions, except Puig, which still requires the use of a second hand to hold the fulcrum engaged with the bottle lip, require a lot of attention to keep the fulcrum on the bottle lip during the repositioning of the lever for each application of the force. They also work with the lever oriented perpendicular to the screw. This excludes one-handed operation. U.S. Pat. No. 984,661 to Halk, and U.S. Pat. No. 280,697 to White also utilizes multiple fulcrum attachment points but stabilizes the fulcrum by making its end an actual collar that goes over the bottle lip. This creates large and bulky fulcrums that cost extra to manufacture. The operator still needs to apply a considerable effort to change the respective attachment points smoothly. Again, they teach an elevated or perpendicular orientation of the lever to the screw that will require the use of two hands and a stabilizing surface.
Previous first-class lever corkscrews, U.S. Pat. No. 280,697 to White, sought to increase leverage by increasing the length of the corkscrew lever. This is satisfactory for a tabletop model but does not solve the leverage problem for a pocket corkscrew.
The problem of the fulcrum staying in place has also been addressed by the following means. U.S. Pat. No. 850,184 to Rees recognized that a slight angle between the screw and fulcrum, that converges toward the screw at the bottle lip, would help hold the fulcrum in place. He only uses this offset angle to assist in holding the fulcrum in place as he also orients the lever perpendicular to the screw. This configuration, again, encourages the fulcrum to fall off the bottle lip and so two hands are required. U.S. Pat. No. 1,213,034 to Sowers uses a notch on the end of the fulcrum. The fulcrum will still fall off while changing the screw's attachment points, unless two hands and attention are given to the operation. Again he orients his lever perpendicular to the screw. U.S. Pat. No. 6,032,553 to Puig makes his fulcrum's ratchet system parallel to the screw, but the fulcrum still has to be held by a second hand since the screw is pivotally mounted and does not hold the fulcrum in place. The free end of his lever is also perpendicular to avoid pinching the operator's fingers on the hand holding the fulcrum in place. Additionally the lever is far from the grasp of a single hand. In summary:    1) second-class lever corkscrews do not allow for one-handed operation.    2) first-class lever corkscrews presently have the following disadvantages:            a) Do not allow for one-handed operation.        b) Have unstable or bulky means of keeping the fulcrum on the bottle lip.        c) Are sensitive to the distance between the pivotal mounts of the fulcrum and screw on the lever.        d) A straight-out pull on the cork is hard to achieve consistently.        e) Leverage has been hard to increase without awkward means.        f) The bottle needs to be stabilized with a hand and a support surface.        